Makefile: add comment wrt running go get twice
Makefile: add comment wrt running go get twice

Signed-off-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

dustinkirkland/lxd,yura-pakhuchiy/lxd,hallyn/lxd,pcdummy/lxd,hallyn/lxd,atxwebs/lxd,dustinkirkland/lxd,ollie314/lxd,pcdummy/lxd,georghopp/lxd,yura-pakhuchiy/lxd,hallyn/lxd,lxc/lxd,mjeanson/lxd,lxc/lxd,atxwebs/lxd,stgraber/lxd,Skarlso/lxd,ollie314/lxd,hallyn/lxd,Skarlso/lxd,erikmack/lxd,dustinkirkland/lxd,stgraber/lxd,mjeanson/lxd,lxc/lxd,akshaykarle/lxd,hallyn/lxd,jsavikko/lxd,Skarlso/lxd,techtonik/lxd,stgraber/lxd,stgraber/lxd,mjeanson/lxd,jsavikko/lxd,erikmack/lxd,lxc/lxd,hallyn/lxd,techtonik/lxd,akshaykarle/lxd,pcdummy/lxd,georghopp/lxd,chrisglass/lxd,ollie314/lxd,yura-pakhuchiy/lxd,lxc/lxd,chrisglass/lxd,chrisglass/lxd,lxc/lxd,stgraber/lxd,jsavikko/lxd,atxwebs/lxd,erikmack/lxd,atxwebs/lxd,stgraber/lxd,georghopp/lxd,stgraber/lxd,techtonik/lxd,Skarlso/lxd,akshaykarle/lxd,lxc/lxd